Telegraph exchange system



0% 1932- J. J. CATOGGE 'EELEGRAPH EXCHANGE SYSTEM Filed June 18, 1931 2Sheets-Sheet POLARIZED INVENTOR J J. CA T0 665 By @M A TTORNEV PatentedOct. 25, 1932 iTED STATES JOSE H J. OATOGGE, OF BROOKLYN, NEW/V YORK,ASSIGNOR TO TORIES, INCORPORATED, OF NEW YORK, N.

PATENT OFFICE BELL TELEPHONE LABORA- Y., A CORPORATION on NEW YORKTELEGRAPH EXCHANGE SYSTEM:

Application filed June 18,

a subscribers station or with another operator connected to the system.A telegraph system of this type is described in the specification ofLocke-Kinkead application Serial No. 459,684, filed June 7, 1930, thedescription of which specification is hereby made part of the presentspecification as if fully included herein.

An ob ect of this invention is to enable convenientand efiicientsupervision of an operators printer circuit at a central oificeswitchboard.

A particular embodiment of this invention comprises a supervisorsprinter circuit for monitoring on an operators printer set at thecentral ofrice of a telegraph exchange system. Keys are provided for thecircuit, individual to each operators position, for connecting thesupervisors circuit with any of a plurality of operators sets at theswitchboard. Peg

count registers indicate the number of incoming calls answered by theswitchboard operators. Key switching means associated with thesupervisors printer enable the supervisor to initiate an outgoing callover a trunk circuit to the switchboard or to answer a call incoming tothe circuit. An indicating lamp in the circuit is utilized to attractthe attention of the supervisor whenever an incoming call is connectedto the supervisors trunk circuit. The apparatus comprising thesupervisors circuit may be located, if desired, at a desk immediatelyremoved from the switchboard.

A. feature of this invention is the peg count register indicatorarrangement in the supervisors circuit for registering the number ofcalls answered by an operator at a position of the switchboard.

Another feature lies in the key switching means for initiating a. callfrom the supervisors desk and for connecting the printer set thereatwith an operators circuit for monitoring purposes.

A further feature is a circuit scheme for 1931. Serial No. 545,213.

indicating to the supervisor that a call is being routed to thesupervisors desk.

Other objects and features will appear in the subsequent detaileddisclosure.

Referring to the drawings,

ig. 1 illustrates schematically a supervisors printer circuit, withassociated peg count register and trunk circuit equipment. Thissupervisors circuit is shown in connection with an .operators printercircuit and a cord circuit, and

Fig. 2 illustrates a further modification of the supervisors printercircuit wherein the supervisors printer operates in multiple with theoperators circuit instead of being serially connected thereto as shownin Fig. 1.

Referring to Fig. 1, there is shown at the central office an operatorsprinter circuit 1 comprising a printer set and associated relayequipment. This printer circuit is used for communicating over cordcircuit 2 with any subscribers printer station A connected to theexchange system and terminating at the central oflice in jack 3 which isthe terminal point of lines T and R extending from subscribers station Ato the central oflice. Cord circuit- 2 includes a known type of repeatercircuit which comprises four polar relays for repeating signal impulsesreceived from one line section to another line section with which it isassociated. Such a repeater circuit is more fully described in thepatent to J. M. Fell, No. 1,479,430, issued January 1 1924 to whichreference is made for a more complete understanding. A supervisorsprinter circuit 4 with associated peg count register equipment isprovided for monitoring and supervisory purposes.

It to be understood, of course, that cord circuit 2, and the lineequipment associated with jack 3 are only illustrative of any apparatuswhich may be used to accomplish the objects of this invention. In actualpractice, other cord circuits similar to 2 and other line jack circuitssimilar to the one shown are employed. A plurality of operators printercircuits may also be used, each circuit being indivicual to an operatorsposition. The subscribersstati'on circuit at A may be of the typedescribed in the Locke-Kinkead application Serial No. 459,684, mentionedhereinbefore.

The manner in which a connection is established will now be described.

Assuming that subscriber A desires to initiate a call, a start key atthe subscribers printer station (which forms no part of the presentinvention) will be pressed causing the operation of mechanism which willserially connect lines T and R through the subscribers equi ment andcause the operation of relay 5 in t e line jack circuit, in turn,lighting lamp 6. This circuit is traced from battery through the windingof relay 5, contact of jack 3, T of the line, through the equipment atsubscribers station A, back over R of the line to ound through the lowercontact of jack 3.

he operation of relay 5 will light lamp 6 on a circuit traced fromground on its armature and contact to battery through the lamp.

The operator at the central ofiice, observing the lighted lamp, willanswer the call by insertin answering plug 7 of cord circuit 2 into jac3 of the subscribers line. This action extinguishes the lamp 6 byopening the contacts of jack 3 and releasing relay 5. The insertion ofplug 7 will complete a circuit from positive battery 9 on the ring ofcord 7 through jack 3 and ring side R of the line, back over tip side Tof the line and tip of cord 7 through the line windings of polar relays11 and 10, contact of polar relay 12 to negative battery on the contactof operators key 14. The position of the relays will now be as shown inthe drawings.

The operator connects her telegraph rinter set to the cord circuit byoperating ey 14 which transfers the line circuit from negative batteryon key 14 to negative battery in the supervisors circuit. This circuitmay be traced over the lead a through the winding of polarized relay 15in the operators circuit, tip of operators jack 16, tip of operatorsplug 17, sending contacts 19, tip of operators plu 18, tip of jack tonegative battery over lea on the contact of key in the supervisor scircuit. The operation of key 14 connects the operators printer inseries with the answering side of the cord circuit repeater.Consequently, communication may now take place between the operator andthe subscriber through the cord circuit and over the line to which thecord is connected. Relay 15, in

operating, causes the operation of relay 21 from battery through theoperated contact of relay 15, winding of relay 21, sleeve of jack 20,plug 18, winding of printer magnet 22, plug 17, sleeve of jack 16 toground.

Under normal conditions, when the operators set 1 is not connected tothe cord circuit, the circuit through the a lead is opened. The armatureof relay 15 is then held against its a: contacts by a local biasingcurrent and relay 23 is kept operated from battery through the normalbreak contact of relay 21, winding of relay 23, sleeve of jack 20, plug18, winding of printer relay 22, plug 17 to ground on sleeve 16 holdingup printer magnet 22. It is understood, of course, that the printermotor is started by actuating a switch at the operators contactoperating relay 21, as previously de-' scribed, and releasing relay 28.The printer will now be under control of relay 15. Relay 21 is designedto be a slow-release relay so that it will remain operated while relay15 is following the printer signals either received from the line orsent to the line from the printer keyboard. Relay 23 may also serve toindicate to an operator that a line signal has already been answered byanother operator or that the line to which the operator is connected isopen. This forms no part of this invention and is described in detail inthe Locke-Kinkead application Serial No. 459,684 hereinbefore mentioned.

The operator being now connected with the subscribers printer may sendthcwordOpcrator or Opr. which is typed on the receiver unit of thesubscribers printer A. The subscriber may answer by transmitting to theoperators printer set information regarding the called subscribers line.The operator having obtained the information (let us suppose) that thecall is to a local subscriber to whom she has direct access, thenconnects plug 8 into jack in the called subscribers line. The insertionof plug 8 into jack 30 of the called subscribers line causes theoperation of relay 24 in the cord circuit, in turn. connecting the tipof cord 8 through the line windings of relays 13 and 12 in the repeatercord circuit to battery on the contact of relay 10. The operator may nowring the subscriber by operating ringing key 51 which will connectalternating current from source of supply 52 to the tip of plug 8associated with the tip side of the called subscribcrs line circuit.\Vhen the subscriber answers the incoming call signal, the transmissioncircuit will be in condition for communication between both subscriberswith the operator monitoring or listening in. If desired, the operatormay restore key 14 to normal, thus permitting the operators printer 1 tobe used for answering calls incoming from other subscribers stationsover other cord circuits and associated key equipment.

The operation of the supervisors printer and peg count monitoringcircuit will now be described. Returning to the circuit connec- 1together.

tion under consideration when the operators printer set at theswitchboard has answered the subscriber, it will be recalled thatnegative battery for the operators printer set was obtained over the 9lead through key 25. Assuming that the supervisordesires to monitor onthe switchboard operators printer, the supervisor will operate keyassociated with the particular position upon which she wishes tomonitor. This action will transfer the 9 lead from the negative batteryon the contact of relay 25 to the lower make contact of key 25 throughthe other keys (designated associated with other positions, lower leftbreak contact of key 26, then to upper right break contact of the samekey to one winding of relay 2?, back over the upper left break contactof key 26, upper left make contact of key 25, upper right break contactof key 26, left make contact of key 26 to negative battery 28, operatingrelay 27 in the supervisors printer circuit. It will be noted that thesupervisors set may only receive signals over this circuit since thesending contacts of the printer are now short-circuited. This path istraced from the tip of jack 29 in the printer circuit, upper makecontact of key 25 to the tip of jack 31. The circuit for the supervisorsset is similar to the circuit for the operators printer set 1,previously described. Relay 27 is normally held to its 00 contact by thebiasing battery flowing through one of its windings. A closed circuitmay be traced from battery of relay 27 through the break contacts ofrelay 32, sleeve of jack 29', sleeve of operators cord 33, winding ofprinter magnet 34, sleeve of plug to ground on the sleeve of jack 31,thus normally holding the printer magnet 34 I operated. The operation ofrelay 2'? when connected in a circuit operates relay 32 on a path tracedfrom battery on the armature and make contact 3 of relay 2?, win ding ofrelay 32, sleeve of ack 29, sleeve of plug 33, winding of magnet 34 toground on sleeve of ack 31 and plug 35. Relay 32 is designed as aslow-release relay. Therefore, it will remain operated while relay 27 isfollowing either the received or sent line signal impulses.

When the printer is not in use magnet 34 is held locked, thus preventinga free whirling of the printer set. lVhen the printer is in use andrelay 32 is operated, the printer magnet is under control of relay 27.The motor for the printer will run continuously when the printer switchis on. i

An advantage of this arrangement is that the operators printer circuitand the supervisors printer circuit are serially connected The receptionof signals on the supervisors printer, when monitoring on an operatorsposition, is an indication that the circuit is properly connectedthrough the opera-tors printer circuit to the cord circuit.

To provide means for checking the peg count, key 25 is so arranged thatby one oper ation of the .key all springs on the left and the peg countset of the operator. A Each operators position has an individual key 36located at the position. Associated with key 26 are relays 37 and 38 anda register 39. At the supervisors desk is a duplicate set of relays and41 and a register 42, also lamp 43.. WVhen the operator has received oranswered a call, she presses key 36 which completes a circuit fromground on key '36, through winding of relay 37 message register relay 38to battery, operatingrelays 37 and 38. Relay 37 in operating placesground on its own'winding to short-circuit itself. This ground alsoserves the additionalpurpose of insuring the operation of relay 38. Thelatter relay in operating actuates register 39 which records all calls.Relay 37 in short-circuiting itself falls back and releases relay 38 andregister 39. Relays 40 and 41 and register 42 function in the samemanner since the ground from key36 traces 'a path through the operatedcontacts of key 25 to operate relays 40 and 41. Indicating lamp 43 isadapted to light up upon the operation of relay 40 on a circuit tracedfrom battery through lamp 43 to ground on the contact and armature ofrelay 40. This lamp is a visible indication to the supervisor that theoperator has pressed her peg count key. Registers 39 and 42 will operateand lamp 60 will light up simultaneously. It is to be understood, ofcourse, that key 25'is located at the supervisors desk and is individualto each position, although relays 40 and 41, register 42 and lamp 43 maybe common to a plurality of keys 26, if desired. The supervisors desk isalso provided with several trunk circuits for receiving calls and makingoutgoing calls over the switchboard in the same manner as an ordinarysubscriber would do these things. Each trunk circuit has associated withit a three-position key 26, an alternating currentrelay 44, a lamp andconnections T and R leading to a line jack circuit similar to that shownat the switchboard in connection with subscribers station A. I

"When as incoming call is received over the T and R leads, relay 44 willoperate on a circuit traced from the ringing current at the sending endof the line over T of the line, through the secondary winding of A. C.re lay 44, through the condenser to ground on the lower break contact ofkey 26. In

operating, relay 44 will lock up over its primary winding and backcontact through key 26 to ground. From the other set of c0ntacts ofrelay 44, lamp 45 will light and auxiliary signal relay 46 will operateto ground, in turn, operating bell 47 through key 48.

' When key 26 associated with the indicated ing contacts of printer,

tmnk is thrown to the left or print position, ground will be removedfrom the circuit and relay 44 will release, extinguishing lamp andreleasing the auxiliary signal bell 47. The printer of the supervisorscircuit will then be bridged across the tip lead T and ring lead R ofthe trunk line on a path from R, left upper inner make contact of key26, ri ht upper break contact of key 26, tip of jac 29, tip ofsupervisors plug 33, sendtip of plug 35, tip of jack 31, winding ofprinter relay 27, right .upper inner break contacts of key 26, leftlower inner make contact of key 26 to tip lead T of the trunk line.Communication between the supervisor and the calling party ma now takeplace.

ey 26 is a special three-position key. If thrown to the right or holdposition, all contacts shown on the entire key will be actuated.Assuming that the supervisor wishes to hold the trunk line over which acall has just come in while she desires to answer acall incomin overanother trunk circuit, she will then t row key 26 to the hold position,thus actuating all contacts on the key and disconnecting the supervisorsprinter relay from the first trunk line and replacing the printer set byresistance 49. If desired, resistance 49 B may be omitted altogether anda short circuit connection used instead to replace the printer set whenkey 26 is thrown to the hold posi tion. The circuit is traced from leadR of the line, left inner upper make contact of '1- key 26, right lowermake contact of the same key, resistance 49, right lower outer makecontact of key 26, left lower inner make contact of key 26 to tip T ofthe line. The supervisor is then free to receive calls or initiate callson another trunk.

When the supervisor restores key 26 to its normal position from eitherthe print or hold ition on the completion of a call, the ring side R ofthe line is grounded on the left upper inner break contact. This groundmay,

in turn, be used to light a lamp in the cord circuit at the switchboardto act as a disconnect signal to the calling operator, if desired. Thisfeature, however, forms no part of this invention. It is described indetail in the Locke-Kinkead application supra. The tip lead T of theline is again connected through relay 44 and the condenser 50 to groundon key 26.

If it is desired to make an outgoing call, key 26 is operated to theleft or print position, in which case, the printer line relay 27 isbridged across the tip of lead T and ring lead R of M the trunk therebyoperating the line jack lamp at the switchboard. This circuit throughthe key is the same as that traced when the supervisor had operated key26 to the print position to answer an incoming call. I

Fig. 2 illustrates a modification of the supervisors circuit wherein thesupervisors printer may be arranged to operate in multiple with theoperators circuit over the 9 lead. This is efl'ected by connecting the 9lead to a contact on an auxiliary relay.

One advantage of this modified arrangement is that the insertion of thesupcrvisors circuit for monitoring purposes cannot affect the operatorscommunication circuit to the subscriber, and thus cause a momentaryopening of the si naling path. Such momentary opening of t 1e line mayinform the operator of the presence of the supervisor on the circuit andthus defeat the purpose which the monitoring feature is intended toaccomplish.

The operator connects her telegraph printer set to the cord circuit byoperating key 14 which transfers the line leading to the cord circuitfrom negative battery on key 14 to negative battery in the operatorsprinter circuit. This circuit is traced through one winding of polarizedrelay 15, tip of operators jack 16, tip of operators plug 17, sendingcontacts 19 of the printer, tip of plug 18, tip of jack 20 to negativebattery. Current flowing through the a lead will operate relay 15 andcause it to follow all printer s gnals, operating, in turn, polarizedrelay 55.

\Vhen operators key 14 is not actuated the a lead will be open and thearmature of relay 15 will be held against its marking contact by thebiasing current through its upper winding. This normal position of relay15 will energize one winding of relay 55 in such manner as to hold thearmata rc of relay against its marking contact, which has groundconnected thereto. This last circuit is traced from battery through themarking Contact and armature of relay 15, one winding of rela 55, sleeveof jack 20, sleeve of plug 18, wlnding of printer magnet 22, sleeve ofplug 17 to ground on the sleeve of jack 16. Thus the printer magnet 22is held locked up, preventing a free whirling of the telegraph set.

The operation of relay 15, in accordance with the signals transmittedover lead a to the cord circuit, will operate relay which, in turn, willsend signals to the supervisors circuit over the 9 lead by opening orclosing the circuit on the armature of the relay.

The operation of: the supervisors printer circuit will now be described.When the printer set is not connected for communication, printer magnet34 will be held up on a circuit traced from positive battery on thearmature and marking contact of relay 27, sleeve of jack 29, sleeve ofcord 33, winding of relay 34, sleeve of cord 35 to negative battery onthe sleeve of jack 31, thus preventing a free whirling of the printerset. Relay 27, when not connected in a communication circuit, isenergized by a biasing current through one of its windings in adirection to hold its armature against its marking contact, as indicatedin the drawings. This circuit is traced from positive battery 57 througha 4800 ohm resistance to ground through the winding of relay 27 It is tobe noted that the potential of point P is now positive. with respect tothe winding and the current is in such direction as to hold the armatureon its marking contact. The opera tion of peg count key 25 in thesupervisors circuit will connect the supervisors printer to theoperators circuit over the 9 lead. This circuit is traced from lead 9,lower inner make contact of key 25, through the other peg count andtrunk circuit keys to the left inner break contact of key 26, rightinner break contact of the same key, the line winding of relay 27, tipof jack 31, tip of plug 35, sending contacts of printer, tip of plug'33, tip of jack.

29, right and left upper break contacts of key 26, to positive battery.Relay 27 will followthe printer signals, in turn, operating printermagnet 34. The operation of key 25- a'lsoconnects negative battery 56through a 2400 ohm resistance, through the lower make contacts of key 25to the biasing winding of relay 27. This action changes the potential ofpoint P of relay 27 from positive through a 4800 ohm resistance tonegative, thus tending to move the armature of the relay to its open orspacing contact. However, the current through the line winding is morethan sutficient to keep relay 2'? in: its normal marking position. Thetransmission of a space signal over lead 9 will open the circuit throughthe line winding of relay 2? and cause the armature to move to itsspacing contact.

An incoming call to the supervisors desk is received over the T and Rleads of the trunk circuit. In such case, relay 44. will operate on acircuit traced from ringing current at the sending end of the lineoverlead T through condenser 50, one winding of relay 44 to ground onthe break contact and armature of relay 56. In operating, relay 44 willlock up on a circuit traced from ground through its upper winding andmake contact, to battery on the break contact of relay- 58. Theoperation of relay.- 44 will light lamp 45 and operate auxiliary signalrelay 46, in a manner similar to that hereinbeforedescribed inconnection with Fig. 1. The supervisor, observing the lighted lamp, willactuate key 26 associated with the lighted trunk circuit to the left orcalling position. This action will connect the printer set forcommunication with the incoming subscriber. The actuation of key 26 willapply ground to operate relay 56 from the lower make contact of key 26.The operation of relay 56 will open the locking up circuit for relay 44,which will release, in turn, extinguishing lamp 45 and re leasing relay46.

The supervisors printer willbe bridged across the T and R leads ona'circuit traced from R, the upper left make contact of key 26, upperright break contact of the same key, 7

tipof jack 29, tip of plug33, sending contacts of printer, tip of plug35, tip of j ack. 31,'li ne winding of relay 27, right inner breakcontacts of key 26, left inner make contacts of key 26, to T of thetrunk circuit.

It is to be noted that the actuation. 0t, key 26. also changes: thepotential: of point P of; relay 2-7 from positive to negative, in thesame manner as hereinbectore described connection with the actuation ofkey 25. Negative; battery 56 connected through a 2400' ohm resistance topoint P through the left lower innermake contact of key 26:, when: th skcyiis thrown.

If the supervisor wishes to hold the call, key 26 will be thrown to. thehold position. In this position, all contacts. of the right and leftsides of the key will be made. The su pervisors line relay 2:? will bedisconnected from the and will be replaced by a short circuit bridgedacross the T and R leads of the trunk circuit. This. circuit is tracedfromzT left inner make contacts of jack 26, right inner make contacts.of the same key, left upper inner make contacts, to lead R of the trunkcircuit. It is to be understood that, if desired, a: resistance may beinserted in the short-circuiting trunk. To initiate a call over thetrunk circui't to the switchboard, key 26 will be actuated to the leftor calling position. This action will bridge the supervisors printer setacross T and: R in the same manner as described in connection withanswering a call incoming over the trunk circuit.

WVhen key 26 isthrown to its normal or disconnected position, the ring'Rof the trunk circuit is grounded at the key to cause the lamp in thecord circuit associated with the trunk to light.

It is apparent that various modifications may be made in this inventionto suit diiierent circuit arrangements without departing from the scopeof this invention.

What is claimed is:

1. In a telegraph exchange system having opera-tors telegraph printercircuits, a supervisors printercircuit comprising a telegraph printerset, a switching device for associating said supervisors telegraphcircuit with an operators telegraph circuit for monitoring purposes, atrunk line, and an addit onal switching device in said supervisorscircuit for signaling an operator over said trunk line for making a.call over the telegraph system.

2. In a telegraph exchange system, in combination, a printer set, agroup of keys, each key being individual to an operators position, andcircuit means for operatively connecting said printer set with anoperators printer circuit upon the operation of a. corresponding one ofsaid keys.

3. In a telegraph exchange system, a supath bridged across the pervisorsprinter circuit compris ng a printer set, circuit means associated withsaid set and switching means for operatively connecting said circuitmeans with an operators position for supervisory purposes, saidsupervisors printer set being responsive to signal impulses receivedover said circuit means and being disabled to transmit signalimpulsesover said circuit means when so connected. 7' t 4. A telegraph exchangesystem of the type which employs a plurality of operators telegraphprinter sets at the switchboard for answering signals characterized inthis that thereis provided for supervisory purposes a; supervisorsprinter circuit comprising a telegraph printer and circuit means notunder the control or observation of said operators for connecting saidsupervisors printer with any of'said operators printer se T 5. A pegcount circuit for a group of operators telegraph positions comprising agroup ofkeys, each ey of said group being individual torrand located atan operators sition, a plurality of registers, each register beingindividual to an operators position and adapted to respond to theoperation of the particular key of said group which is associated withthe same position, an additionaltregister, and means to connect saidadditional register in said circuit for operation upen the actuation ofone of said keys.

6. A peg countcircnit for an operators telegraph position comprising akey, two indicators responsive to the operation of said key and meansfor disconnecting one of said indicators without affecting theoperationof said other indicator.

-7. A peg count register circuit comprising a plurality of indicatorsand a plurality of keys, each of said indicators being responsive to theoperation of a different one of said keys, an additional indicator andmeans for associating said additional indicator with any one of saidplurality of indicators for simultaneous operation therewith.

8. A peg count circuit for a group of operators telegraph positionscomprising a set of keys arranged together, each" key being individualto an operators position, a second set of keys, each key of said secondset being individual to and located at an operators position, a registerand a lamp indicator common to said first set of keys'and located withsaid first set of keys, circuit means associated with said register andlamp indicator for operating the register and lighting the lamp, saidcircuit means being responsive to the successive operations of a key insaid first set and a key in said second set associate with the sameposition. 9. In combination, in a telegraph exchange system, subscriberlines, an operators printer circuit for answering calls incoming to acentral ofiice switchboard over said subscriber lines, a supervisorsprinter circuit and switching means for serially connecting saidsupervisors printer with said operators printer, said switching meansbeing operatively independent of the connection of said operatorsprinter to said subscriber lines.

10. In a telegraph exchange, a cord circuit, an operator printerconnectable at will to said cord circuit, an extension circuit throughsaid operator printer to a source of potential, and a key :for cutting asupervisor operator printer into said extension between said source andsaid operator printer.

11. In a telegraph exchange system, a link circuit, an'operator printerconnectable to said link circuit to be operated thereover, and asupervisor printer connectable at will to said link circuit to beoperated tl'iereover when said operator printer is connected thereto, incombination with devices whereby said supervisor printer may beconnected to or disconnected from said link circuit, said devicesincluding contacts whereby the operability of said operator circuit oversaid link circuit is maintained.

12. A telegraphic exchange comprising a plurality of operator linkcircuits for connection to subscriber lines, a plurality of operatorprinter circuits, a supplemental relay in each printer circuitcontrolling a path extending to a supervisor operator position, anddevices in said path for connecting a supervisor operator printer intosaid path.

13. In a telegraph exchange system, an operator circuit including atelegraph printer set for answering subscribers calls, a key forconnecting said printer set into a subscriber circuit, said operatorcircuit includmg an extension through a supervisor operator positionwhereat is located a supervisor operator telegraph printer set, and adevice at said position for cutting said supervisor operator printer setinto said operator circuit at will. i

14. A printing telegraph system comprising a switching positionincluding an operator printing telegraph set, a plurality of incomingcircuits terminating at said position. a connecting device forconnecting a selected incoming circuit across said operator printingtelegraph'set, a holding path other than a path through said operatorsprinting telegraph set, and means for holding said incoming circuitclosed across said holding path whereby after answering a call upon theincoming circuit said circuit may be held closed while the operator isperforming other operations.

15. In a telegraph exchange system, an incoming line terminating in ajack, and a supervisor operator printing telegraph set in combinationwith two channels of distinctive operating characteristics over whichsaid set may be operatively connected to said line.

16. A system in accordance With the immediately foregoing claim in whichone of said channels includes means whereby said operator set isconnected for transmission and reception and the other includes meanswhereby said set is connected for reception only.

1?. In combination, in a printing telegraph exchange, an interconnectinglink circuit for connecting subscriber lines, an operatorcircuitincluding a telegraph sending and receiving set having sending contacts,plug and jack instrumentalities for connecting said set into operativerelation to said link circuit, and devices connected to said plug andjack instrumentalities render the sending contacts of said setinoperative when the plug and jack instrumentalities are conditioned toconnect said set into operative relation with said link circuit.

In Witness whereof I hereunto subscribe my name this 16th day of June,1931.

JOSEPH J. CATOGGE.

